Inhibition of Reactive Nitrogen Species Effects in Vitro and in Vivo by Isoflavones and Soy-Based Food Extracts

Abstract

Recent studies have shown that soy isoflavone inhibits inducible nitric oxide (NO) synthase activities and is reported to have peroxynitrite scavenging ability. Consequently, we investigated whether isoflavones (daidzein and genistein) and extracts from soy-based products (miso, soymilk, tofu, soy sprout, black soybean, soybean, and yuba) would inhibit the reactive nitrogen species (RNS) effect in vitro and in vivo. In the in vitro experiments [including the protection of cellular DNA from peroxynitrite or sodium nitroprusside damage, an inhibitory effect on nitric oxide production from lipopolysaccharide (LPS)-induced RAW 264.7 cells, and nitric oxide scavenging ability], extracts from soy-based foods showed a potent antioxidant activity and an inhibiting effect on RNS activity. These effects were correlated with total isoflavone content. In the in vivo experiments, rats were given isoflavones (4.0 mg/kg bw) or soy-based product extracts (1.0 g/kg bw) orally for 1 week and were injected with vehicle H(2)O (1 mL/kg bw) or LPS (10 mg/kg bw) on the day 7. Twelve hours after treatment, the rats were killed, and blood serum was collected for analysis. The intraperitoneal administration of LPS resulted in an increase in serum nitrite, nitrate, and nitrotyrosine concentrations. These are stable metabolite end products of nitric oxide, to 4-, 16-, and 5-fold levels, (4, 10 microM and 58 +/- 14 pmol/mL), of the placebo control, respectively. Results showed that oral administration of isoflavones and extracts from soy-based products significantly decreased serum nitrite, nitrate, and nitrotyrosine levels in LPS-induced rats. This study demonstrates that soy isoflavone supplementation may inhibit RNS-induced oxidation both in vitro and in vivo.

Teores de isoflavonas e capacidade antioxidante da soja e produtos derivados

“…Recentemente, YEN & LAI [28] reportaram que a suplementação com isoflavonas purificadas (daidzeína e genisteína) ou extrato metanólico 80% obtido a partir de alguns produtos de soja, tais como tofu, inibiu a oxidação de espécies de nitrogênio reativo in vitro e in vivo. A inibição foi correlacionada positivamente com o conteúdo total de isoflavonas nos extratos.…”

Chemical and bioactive characterization of pot-pollen produced by Melipona and Scaptotrigona stingless bees from Paria Grande, Amazonas State, Venezuela

“…It has been widely demonstrated that flavonoids are very effective as scavengers of reactive oxygen species (ROS): peroxide, hydroxyl and superoxide radicals, as well as against reactive nitrogen species (RNS) like nitric oxide and peroxyl nitrite (Yen and Lai, 2003). Moreover, flavonoids have high affinity for proteins and other biological macromolecules, such as hormones and nucleic acids, and for divalent ions of metals; and also have high catalytic ability for the electron transfer and act as radical scavengers.…”

Soy Isoflavone Supplementation Alleviates Oxidative Stress and Improves Systolic Blood Pressure in Male Spontaneously Hypertensive Rats

“…Until now, the anti-hypertensive qualities associated with isoa vone have been ascribed mainly to its cholesterol-lower ing effect (12). Recent recognitions of soy-isoflavones as free radical quenching agents both in vitro and in vivo (13,14) have led us to hypothesize that the antioxidant abilities of isoflavones can influence the stability of endothelium-derived vasoactive agents , such as NO, and thus contribute to a decline in blood pressure . The aim of this study was to investigate whether isoflavone supplementation alters the progression of blood pres sure by the modulation of NO and relief from oxidative stress in male spontaneously hypertensive rats.…”

“…Inoue and Kawanishi (41) have demonstrated that superoxide rad ical reacts with the NO to form peroxynitrite, and that peroxynitrite in turn induces DNA damage through an active intermediate, the reactivity of which is similar to the hydroxyl radical (OH'). On the other hand, Yen and Lai (42) found that the antioxidant activity of isofia vones and soy-based food (e.g. soybeans , soy milk, tofu, etc.)…”